In
1973, more than 4000 people in Michigan were exposed to polybrominated
biphenyls (PBBs) because of accidental food contamination. This study
examines the impact of PBB exposure in the womb and after birth on the
development of puberty in girls contaminated by the accident. Blanck et
al. report that girls exposed to relatively high levels in the
womb began menstruating up to a year earlier than those with lower levels.
Perinatal exposure was also associated with earlier public hair development.

What
did they do?
Blanck et al. contacted all girls (and/or their mothers) at least
5 yrs of age that had been born during or after the PBB incident whose
mothers were participants in the Michigan PBB registry and invited them
to participate in a study of pubertal development. Information was obtained
from 327 girls. Serum measurements of PBB exposure had been obtained at
the time of enrollment in the PBB registry (1976-1979). Six percent of
participating mothers had breast milk PBB measurements. Mathematical models
were used to estimate in utero exposure based on the serum and breast
milk measurements. PCB measurements were also available for 85% of participants.

Study
subjects (and/or mothers) were asked about various aspects of pubertal
development, including age at menarche and standard assessments of breast
and pubic hair development, as well as weight and recent physical activity.
Mothers were also interviewed about their smoking and alcohol use during
pregnancy.

What
did they find.
The average estimated PBB exposure in the womb was 17.3 parts per billion,
while average in utero PCB exposure was 5.6 ppb.

At
the time of the study, 64% of the girls had reached menarche. Their average
age at menarche was 12.3 yrs.

"Breastfed
girls exposed to high levels of PBB in utero (at least 7 ppb) had
an earlier age at menarche than breastfed girls exposed to lower levels."
Ages at menarche for these two groups were 11.6 yrs and 12.2-12.6 yrs,
respectively. Girls not breast fed had a slightly higher age at menarche
(12.7 yrs). It would appear that the additional exposure through breast-feeding
added to the impact of in utero exposure, that is the strongest
impact (youngest age at menarche) was seen among girls with higher
in utero exposure who also were exposed through breastfeeding.

PCB
exposure showed no association with age at menarche.

Breast
development: The data were inconclusive. "There was a suggestion
of earlier breast development for breastfed girls with moderate in
utero PBB exposure, but not for breastfed girls with high exposure."